Lubricant and method of preparing same



Patented Aug. 14, 1945 LUBRICANT AND METHOD OF PREPARING A SAME WilliamA. Whittier, Glenview, m., assignor to The Pure Oil Company, Chicago,III., a corporation of Ohio No Drawing. Application October 17, 1942,Serial No. 462,408

11 Claims.

This invention relates to lubricants and to lubricant additives,particularly those additives which have the ability to impart to minerallubricating oils the ability to function satisfactorily under extremepressure conditions and the ability to inhibit metal bearing corrosion.More specifically, the present invention constitutes an improvement overthe lubricant additive and the method of preparing disclosed and claimedin Whittier et al. Patent 2,211,306.

I have discovered that the lubricant additive disclosed in the aforesaidpatent can be improved upon both as to its load carrying characteristicsand as to its viscosity by processing the additive in an oxygen freeatmosphere. Although I have found that the greatest improvement in loadcarrying ability and viscosity of the additive occurs if the sulfurizingstep is carried out in an atmosphere free from oxygen, the viscosity ofthe product is further improved if the phosphorizing step is alsocarried out in an oxygen free atmosphere, although the load carryingcharacteristics of the additive do not appear to be detrimentallyaffected by phopshorlzing in an atmosphere of air.

Heretofore it has been the practice to prepare the additive inaccordance with the aforesaid patent by sulfurizing and phosphorizing inopen kettles in which the mixture had free access to the air. Underthese conditions the viscosity of the resulting additive was relativelyhigh, thereby making the viscosity of the final blend of oil andadditive high because of the comparatively large amount of base (18% byvolume) which it was required to add to the lubricating oil to obtainthe desired load carrying characteristics. By carrying out thesulfurizing step in a closed autoclave from which air is excluded undersuperatmospheric pressure, it is possible to obtain an additive with aviscosity of slightly above 200 to less than 400 seconds SayboltUniversal at 210 F. as compared to viscosities well above 600 when theadditive is made in the presence of air. Moreover, the additive preparedin accordance with this invention may be used in far less quantity inthe oil blend in order to give the same or superior load carryingcharacteristics.

In order to demonstrate my invention, a large number of samples ofsulfurized and phosphorized additives were prepared under differentconditions. In all cases in preparing the additive the followingprocedure was followed: 2177.5 grams of prime lard oil were mixed with125 grams of light mineral oil and 12.5 grams of sulfur monochloride andstirred until a homogeneous mixture was obtained. The mineral oil usedin this mixture was a Gulf Coast lubricating oil having the followingcharacteristics:

To the mixture was added 185 grams of flowers of sulfur. The sulfur wassifted into the mixture while the mixture was constantly stirred. whenall the sulfur had been added to the mixture it was charged into a onegallon autoclave fitted with a stirrer. The autoclave was then flushedwith nitrogen to expel any air present and was then sealed. Nitrogen orhydrogen sulfide pressure was maintained above the mixture in theautoclave. In certain experiments the autoclave was left open in orderto compare the effect of air with inert gas in the processing of theadditive. The autoclave was maintained at a temperature of 330 to 340F., and in some cases at 360 F., for either 3 /2 or 7% hours and wasagitated during the entire time. The product was then pumped from theautoclave and cooled.

The sulfurized product prepared in the foregoing manner was tested forcopper strip corrosion, viscosity and load carrying ability. In themajority of samples the sulfurized oil made, as just described, wasfurther treated by mixing therewith 10 grams of phosphorus sesquisulfideand the mixture again placed in the autoclave and heated for 5 hourswith stirring at 220 to 230 F. In'those experiments in which air wasexcluded the autoclave was flushed with nitrogen and sealed and thereaction conducted at low superatmospheric pressure in a nitrogen orhydrogen sulfide atmosphere. In other experiments which were carried outin the presence of air an open autoclave was used. At the end of theheating period the base was pumped from the autoclave and cooled. Eachsample of finished material was tested by the copper strip corrosiontest and found to be non-corrosive.

Samples prepared, as just described, were blended with minerallubricating oil in various amounts and tested on the 'Iimken testingmachine to determine load carrying ability. The oil used in preparingthe-blend was a mixture of the oil described in Table I and another GulfCoast lubricating oil having the following characteristics:

Table II Flash point, F 510/520 Fire point, F 590/600 Vis. S. U. 210 F150/165 Pour point, F 25 max. Color, N. P. A Bmax. Carbon residue, percent lmax.

These oils were blended with the base so that the resulting blend hadapproximately the following characteristics:

Table III Vis. S. U. 130 F. in seconds- 1,100-1,215 Vis. S. U. 210 F. inseconds 160-- 170 Pour point, F., maximum 15 F.

The results obtained on a number of these blends are given in thefollowing Table IV:

mosphere of air on the viscosity of the'product which was bothsulfurized and phosphorized in the atmosphere of air. Comparing samplesi to 3 with samples It and I5, it is evident that the exclusion .of airduring the sulfurlzation step had a very beneficial eflect in keepingdown the viscosity of the additive and materially improved the loadcarrying ability of the additive. 10 per cent of this additive whenadded to the mineral oil carried a much greater beam load on the Timkenmachine and almost withstood as high a pressure as did 18% of sample 1.

When samples 14 and 15 are compared with samples 4 to 9 it will beapparent that although phosphorization in air does increase theviscosity of the final material somewhat the increase is small comparedto the increase resulting from sulfurization in the air atmosphererather than an oxygen free atmosphere. Moreover, phosphorization in airrather than in an oxygen-free atmosphere does not appear to materiallyaffect the load carrying ability of the resulting product.

Table IV Timken tests Per cent Sulfuriza- Suliurization Suliurize-Phosphoriza- Phosphog gzggg Sample vol. of base tion time ressure, tiouatmostion pressure, rization atsaybolt in blend in hrs. 1 5. sq. in.phere lbs/sq. in. mosphere versal at 210 F Beam Pressures, load, lbs.lbs/sq. in.

18 7. 5 Atmospheric Air Atmospheric 650 50 35, 750

14 7. 5 Atmospheric do. Atmospheric 678 51 30, 250

10 7. 5 Atmospheric do Atmospheric 678 43 27, 750

14 3. 5 Atmospheric 335 86 36, 500

10 3. 5 Atmospheric 335 86 35, 250

14 7. 5 Atmospheric 376 86 36, 500

' l0 7. 5 Atmospheric 376 77 34, 250

Lard 87.0 Mineral oi 5.0 Sulfur monochloride .5 Sulfur 7.4 Phosphorussesquisulflde .4

In all cases with the two exceptions noted in the table the temperaturefor sulfurization was maintained at approximately 330 F. In all casesexcept in the case of the blank runs 16 and 17, which were notphosphorized, the temperature of phosphorization was 220-230 F. andphosphorization was carried out for a period of 5 hours.

By referring to the table it will be seen from samples I6 and I! that bysulfurizing the lard oil in an oxygen free atmosphere a sulfurized fattyoil base of relatively low viscosity is obtained. Samples I to 3 showthe effect of an at- It was found, however, that if both thephosphorization and sulfuriaation was conducted in an atmosphere ofhydrogen sulfide not only was the viscosity of the final productextremely low but the load carrying ability was extremely high. 10 percent of this material (see sample 9) carried a considerably greater loadthan 18 per cent of the base made in an air atmosphere (see sample 1).Thus, I have found that if the sulfurization step is carried out in aninert atmosphere, a considerable improvement in viscosity and loadcarrying ability is obtained regardless of What atmosphere is usedduring the phosphorization step. But both these properties are greatlyenhanced by carrying out the two steps in a hydrogen sulfide atmosphere.

The amount of pressure maintained in the autoclave during the cookingdoes not materially aflect either the viscosity or load carrying abilityof the finished product.

Although the invention has been described with respect to treatment oflard oil, it should be understood that the invention is applicable totreatment of fatty bodies in general including various vegetable, animaland marine oils and waxes such as cotton seed, castor, rape seed andsperm oil. It should also be understood that the invention is applicableto sulfurization with either 7 sulfur or sulfur chlorides or anycombination thereof. The proportions of sulfur in the final base shouldbe within the limits of 1 to 20 per cent by weight, but preferablybetween 5 and 7 per cent.

Although the invention has been described using phosphorus sesquisulfideas the preferred phosphorizing agent it will be understood that otherphosphorizing agents such as halides, oxyhalides, oxides and in generalthose phosphorus compounds disclosed in Patent 2,211,306 may be used.The phosphorus content of the finished additive should not exceed 2 percent and is pref erably maintained between .2 and .6 per cent.

The temperature of sulfurization may vary somewhat, but in general ithas been found that it should not be substantially below 320 F. andshould be below 400 F. The temperature of phosphorization must bemaintained within the approximate range of 220 to 230 F. to obtain auniform product of desired characteristics.

In accordance with my invention I have been able to prepare an additivewhich may be added to mineral lubricating oils in relatively smallamounts to impart desirable extreme pressure characteristics to the oilwithout materially increasing the viscosity thereof, thereby permittingthe use of high flash oils. The additive prepared in accordance with myinvention may be used in amounts ranging from as low as .5 to dependingon the particular use to which the lubricant is put. In addition tofunctioning as an extreme pressure lubricant my additive possessesmarked corrosion inhibiting properties so that when added to motor oilsfor lubricating metal bear ngs the bearing corrosion is very noticeablyreduced. Where the additive is intended to function primarily as acorrosion inhibitor for preventing corrosion of metal bearing surfaces,it is effective when used in amounts of .05 to 5 per cent by volumebased on the oil with which it is blended.

I claim:

1. The method of preparing a lubricant which comprises reacting sulfurand a fatty body under pressure at a temperature of 320-400 F. in amaintained atmosphere of hydrogen sulfide substantially free of oxygenand in such amounts as to incorporate from 5 to 7% by weight of sulfurin the fatty body, until the reaction product is non-corrosive asdetermined by the copper strip test and then phosphorizing the reactionproduct at a temperature of approximately 220- 230 F. until the finalproduct is non-corrosive as determined by the copper strip test.

2. The method of preparing a lubricant which comprises reacting fattyoil with from 1 to 10% by weight of sulfur at a temperature between 320and 400 F. under superatmospheric pressure in a maintained atmosphere ofhydrogen sulfide substantially free of oxygen until the product isnon-corrosive as determined by the copper strip test and phosphorizingthe resulting product at approximately 220-230 F. for about 5 hours.

3. Method in accordance with claim 1 in which the product isphosphorized in an atmosphere substantially free of oxygen.

4. Method in accordance with claim 1 in which the reaction product isphosphorized. with phosphorus sesquisulfide in a hydrogen sulfideatmosphere.

5. Method in accordance with claim 1 in which the reaction product isphosphorized with phosphorus sesquisulfide.

6. The method in accordance with claim 1 in which the reaction productis phosphorized with phosphorus sesquisulfide in an atmospheresubstantially free from oxygen.

7. The method in accordance with claim 1 in which the reaction productis phosphorized with phosphorus sesquisulfide in an atmosphere ofhydrogen sulfide.

8. A non-corrosive, stable lubricant having a Saybolt Universalviscosity at 210 F. of less than 400 seconds and high load carryingability, said lubricant being a sulfurized and phosphorized fatty oilhaving a sulfur content of 5 to 7% by weight, and a phosphorus contentof .2 to .6% by weight.

9. Lubricant in accordance with claim 8 in which the viscosity isbetween 200 and 400 seconds.

10. The method in accordance with claim 1 in which the reaction productis phosphorized with phosphorus sesquisulfide in an amount toincorporate from .2 to .6% by weight of phosphorus in the product.

11. The method in accordance with claim 2 in which the reaction productis phosphorized with phosphorus sesquisulfide in an amount toincorporate from .2 to .6% by weight of phosphorus in the product.

WILLIAM A. WHI'IIIER.

